Michael Hannon - still researching his famliy history

I am still reaearching my 2nd grear grandfather Michael Hannon born Dublin around 1831.

Father:Thomas Hannon   Mother: Elizabeth McGourk.

my major brickwall at this time is finding validated history for the named mother of Michael Hannon, Elizabeth McGourk.

I have noted in the majority of family trees relating to Michael Hannon and also in the Irish parish records 1816 - 1860

An entry for a: Elizabeth McGourk, baptisd 30th March 1820  in Dublin, Balbriggin, Diocese: Dublin.

 Her father listed as: Anthony McGuirk, her mother: Anne Byrne.

My problem is that if Michael was born in 1831 and mother being Elizabeth McGuirk/Gourk was born in 1820 then, good lordy, she was only eleven years old, married and a mother!!

I am at a loss where to go now to find any available records relative to her marriage to Thomas Hannon, her birth etc.

I would be grateful for any thoughts, direction etc.

Cheers,

Ssmullen